f338832 Report post Posted May 9, 2009 We have a Workhorse chassis with an 8.1-liter engine. Has anyone changed mufflers and what mileage are they getting? ex1075 Share this post Link to post Share on other sites
traderdude04@yahoo.com Report post Posted June 3, 2009 Since the Workhorse Chassis uses dual freeflow mufflers and pipes, it is usually not necessary to install new pipes. I haven't heard of anyone doing this, but have heard of some changing the mufflers. Share this post Link to post Share on other sites
